WO2009077548A1

WO2009077548A1 - Motor quadricycle structure

Info

Publication number: WO2009077548A1
Application number: PCT/EP2008/067684
Authority: WO
Inventors: Romano Artioli
Original assignee: AUTOMOTIVE RESEARCH TECHNOLOGY & STYLE Società a Responsabilità Limitata
Priority date: 2007-12-17
Filing date: 2008-12-17
Publication date: 2009-06-25
Also published as: ITMI20072355A1

Abstract

A motor quadricycle (2) comprises a chassis (1), a body that defines an interior compartment, a plurality of wheels for ensuring stable support of the quadricycle on the ground, front shock absorbers (31) and rear shock absorbers (32) associated with said wheels (3), electric motor means (14) for allowing said quadricycle (2) to move and a front seat (7) for a driver (D). Advantageously, the quadricycle (2) has an upper load-bearing structure (30) supported by said chassis (1), for defining with said chassis (1) a safety cell in which a driver (D) of the quadricycle can be received in a protected position.

Description

DESCRIPTION Title: "Motor quadricycle structure"

The present invention relates to a motor quadricycle structure as defined in the preamble of claim 1 , which has such a compact size as to be particularly suitable for urban use.

As used herein, the term motor quadricycle is intended to indicate a low- weight vehicle, generally weighing not more than 400÷500 kg, and capable of being stable on the ground, both when parked and running, without requiring any external support means, such as kickstands and the like and of receiving at least one passenger therein, in a protected position. Examples of quadricycles are small four- wheel or three-wheel motor vehicles, with wheels arranged along two different staggered axes.

In cities, the need is increasingly felt of solving or at least mitigating the congestion problems associated with vehicle circulation and parking. This problem is particularly serious when coming closer to downtown. Particularly, in inner cities, roads are so narrow that smooth vehicle circulation and parking are hindered.

While the increasing use of motorcycles, scooters and the like helps to solve traffic and parking problems, it still involves drawbacks in terms of safety and protection from bad weather of the driver and any passenger. In view of the above, an optimal solution to urban transport problems can be found in compact vehicles, such as quadricycles.

In spite of their small size, these quadricycles shall be capable of ensuring a high passenger protection standard.

Particularly referring to compact vehicles, such as quadricycles, the need arises of causing the interior compartment of the vehicle to define a survival cell for preserving the integrity of passengers in case of collisions, and especially, in case of overturns, to create a safety cell.

On the other hand, the need arises of forming said safety cell with a sturdy construction, without excessively increasing the overall weight of the structure, so that the maximum weight allowed by the various quadricycle standards is not exceeded.

Additional concerns are associated with the problem of discharging the stresses exerted on the quadricycle structure upon a front-end collision and the like to the ground, as well as the problems related to noxious emissions of engines, to allow substantially free circulation of quadricycles without being subjected to any kind of restrictions.

This invention is based on the problem of providing a motor quadricycle structure, particularly a quadricycle of very compact size, that has such structural and functional characteristics as to fulfill the above needs and address the above issues, while obviating the above prior art drawbacks.

This problem is solved by a quadricycle structure as defined in claim 1.

Further features and advantages of the quadricycle structure of the present invention will be apparent upon reading the following description of one preferred embodiment thereof, which is given by way of illustration and without limitation with reference to the accompanying figures, in which:

- Figure 1 is a simplified perspective view, with some missing parts, of a motor quadricycle structure of the present invention;

- Figures 2 and 3 are side and top planar views respectively of the quadricycle structure of Figure 1; - Figure 4 is a bottom view of the quadricycle structure of Figure 1; - Figures 5 and 6 are two respective views of the load bearing structure of the quadricycle structure of Figure 1;

- Figures 7, 8 and 9 are perspective views of the chassis of the quadricycle structure of Figure 1; - Figure 10 shows a side member of the chassis of Figures 7, 8 and 9;

- Figure 11 is the top view of Figure 3, with additional parts omitted;

- Figure 12 is a perspective view of the upper load-bearing structure of the quadricycle structure of Figure 1,

- Figures 13 and 14 are two perspective views from two different points of view, of the upper load-bearing structure of the quadricycle structure of Figure 1, including the body part that forms the roof;

- Figure 15 is a partially sectional perspective view of the differential gear unit, the electric motor and gears of the quadricycle structure of Figure 1;

- Figure 16 shows the detail of a connection hinge for the doors of the quadricycle of Figure 1 and

- Figure 17 is a sectional view as taken across line A-A of Figure 16. Referring to the accompanying figures, numeral 2 generally designates a motor quadricycle of the invention.

The quadricycle structure 2 comprises: - a chassis 1 (see Figures 7, 8 and 9);

- an upper load-bearing structure (see Figure 12) supported by said chassis 1, and defining therewith a safety cell 4 (see Figures 5 and 6) in which a driver D and a passenger M of the quadricycle can be received in a protected position;

- a plurality of wheels 3, for ensuring stable support of the quadricycle 2 on the ground, in this example two steerable front wheels 3 and two rear wheels 3, with the rear wheels possibly also being of steerable type;

- a body supported by the chassis 1 and the upper load bearing structure to define an interior compartment;

- mechanical drive means for transferring motion from the motor means to the driving wheels 3;

- front shock absorbers 31 and rear shock absorbers 32 associated with the respective wheels 3;

- suspensions 33 associated with the wheels 3;

- a front seat 7 for the driver D and - a steering unit 5 comprising a steering wheel 6 for driving the steerable front wheels 3 and

- motor means 14 for allowing said quadricycle 2 to move.

The quadricycle 2 further has additional components that typically form the quadricycle equipment. These additional components, which may be of either mechanical or hydraulic, electric or electronic type, are known per se and will not be listed or described herein for simplicity.

In the illustrated embodiment, the quadricycle 2 is of small size, i.e. has a longitudinal dimension A of the order of 200÷250 cm, preferably about 210 cm or little more, a transverse dimension B of the order of 90÷120 cm, preferably about 100 cm and a height C of the order of 140÷160 cm, preferably about 150cm.

The quadricycle 2 extends in a longitudinal direction X-X from a front end to a rear end, as seen in the straight quadricycle direction.

Preferably, the front seat 7 and the back seat 8 are aligned along the median longitudinal line X-X of the quadricycle 2, i.e. along the longitudinal centre line of the quadricycle. Advantageously, the back seat 8 of the quadricycle is oriented in the front direction of the motor vehicle, for optimized utilization of the interior space. Particularly, the passenger P will have the legs slightly set apart, straddling the driver D, and extending along the sides of the quadricycle 2 to the front end. Advantageously, the front seat 7 and the back seat 8 have a backrest, and are configured as armchairs.

Therefore, the interior compartment of the quadricycle 2 can receive two seats, 7 and 8, for two users, a driver D and a passenger P, in tandem arrangement, which can comfortably and safely receive the driver D and the passenger P. The back seat 7 can slide along longitudinal guides to a forward position for the passenger P to get on and off the back seat 8. Alternatively or in addition to the above, the front seat 7 may be also folded forward to the front of the quadricycle, with the whole seat or only the backrest thereof being collapsible.

In this example, the back seat is at a higher level than the front seat 7. Therefore, as mentioned above, the passenger may comfortably sit on the back seat 8 with the legs straddling the front seat 7.

Furthermore, the front seat 7 is in such a relation to the chassis 1 that it can rotate through a predetermined angle, such as 90°, 180° or more, about a vertical axis substantially perpendicular to a seat surface, for the front seat 7 to be oriented towards one side of said quadricycle, i.e. towards one of the two accesses to the interior compartment for the driver D.

Advantageously, the quadricycle structure has removable engagement means

(not shown) which are adapted to engage the front seat 7 to stably hold it in a first angular position in which the front seat 7 is oriented in the direction of travel, to receive the driver D in the correct quadricycle driving position (see Figures 2, 3). These engagement means are releasable by the driver D for said seat to be rotated to one side of said quadricycle as mentioned above. Elastic means operate on the front seat 7 for moving the first seat 7 by a predetermined elastic load into said first angular position. Preferably, said motor means include one or more electric motors 14 for rotatably driving one or more wheels 3.

Here, the quadricycle 2 has a electric motor 14 between the rear wheels 3 and an additional electric motor 14 between the front driving wheels, each electric motor being kinematically connected to its respective wheels 3 for driving them into rotation and acting as an electrodynamic brake upon them, to allow recovery of kinematic energy during the braking steps.

The quadricycle 2 has a plurality of accumulators 15, which are electrically connected with each other and with the electric motors 14.

The quadricycle 2 may be equipped with a single electric motor 14, e.g. operating on the rear wheels, otherwise an electric motor may be provided for each wheel.

In one advantageous aspect, the quadricycle 2 has a motor generator which is designed to act as a power source for supplying power to the electric motors 14 and/or charging the accumulators 15. In the illustrated embodiment, the motor generator is located at the back of the quadricycle 2, substantially between the rear wheels 3, and comprises a current generator 16 and an internal combustion engine 18 for driving the current generator 16.

Particularly, the electric generator 16 is rotatably connected with the drive shaft of the internal combustion engine 18 by motion transfer means, such as a belt drive or a continuously variable transmission (CVT).

The quadricycle 2 further comprises control means for electrically and selectively coupling the accumulators to the electric motor 14 and/or the current generator 16. Preferably, the internal combustion engine 18 is a four-stroke cycle engine having a contra-rotating balance shaft and may be powered either with gas, such as methane or GPL, or with liquid fuel of fossil and/or vegetable origin such as gasoline, diesel oil, rapeseed oil and so forth. For this purpose, the quadricycle 2 has a tank 17 for fossil fuel, and an additional tank 20 adapted to contain pressurized gas.

It shall be noted that the quadricycle 2 has no drive means for operably connecting the internal combustion engine 18 with the wheels 3, the driving wheels being powered by their respective electric motors. This arrangement allows the internal combustion engine 18 to be located in any preferred position, regardless of the position of the driving wheels and without providing a mechanical transmission between the internal combustion engine and the wheels. Thus, the internal combustion engine 18 is only used to drive the electric generator 16 into rotation, to ensure generation of the power required for charging the accumulators and/or driving the electric motors. Advantageously, by placing the electric motor between the two driving wheels 3, the size of the mechanical transmission means required for transmitting torque from the drive shaft of the electric motor to the driving wheels may be minimized.

According to a preferred embodiment, the quadricycle structure comprises a differential unit 19, located between the two opposed rear driving wheels 3, with which it is kinematically connected via respective axle shafts extending substantially transverse to said longitudinal direction X-X.

The rotating shaft 21 of the electric motor 14 extends in the longitudinal direction X-X, and is thus substantially perpendicular to the transverse direction of extension of said axle shafts.

The rotating shaft 21 of the electric motor 14 has a free end that is located substantially below the differential unit 19.

A gear train 22 kinematically connects the drive shaft 21 of the electric motor 14 with the differential unit. This gear train 22 comprises a crown wheel and pinion, with a bevel pinion 26 integrally rotatably connected to the free end of the drive shaft 21. Preferably, the bevel pinion 26 is keyed to the drive shaft 21.

Like for the rear driving wheels:

- the quadricycle comprises a differential unit 19, located between the two opposed rear driving wheels 3, with which it is kinematically connected via respective axle shafts;

- the front electric motor 14 located between the front electrically powered wheels has a drive shaft 21 extending in the longitudinal direction X-X with a free end located substantially below the differential unit 19 and a gear train 22 kinematically connects the drive shaft 21 with the differential unit 19, said gear train 22 comprising a crown wheel and pinion, with a bevel pinion 26 integrally rotatably connected to the free end of the drive shaft 21.

The chassis 1 of the quadricycle 2 has a front portion Ia for supporting the front wheels 3, a rear portion Ib for supporting the rear wheels and a central portion Ic which forms a floor for the quadricycle 2. Advantageously, the central portion Ic has a substantially closed- loop peripheral structure delimited by a peripheral wall 38 of predetermined height H, to define a safety compartment V in said floor, for safely accommodating heavy components of the quadricycle 2, mainly the accumulators 15 and the pressurized gas tank 20. The wall 38 acts as a retention member for effectively accommodating said heavy components of the quadricycle 2, particularly in case of collision.

The wall 38 has a height H of 8 cm or more and not above 15 cm, preferably 10 cm.

The wall 38 is formed of a specially bent sheet profile, with localized reinforced elements associated therewith, e.g. at the corners or connections of the various parts.

In this example, the profile that forms the wall has a substantially C-shaped cross section.

Advantageously, the substantially closed-loop structure is closed by a lower panel at its bottom and by an upper panel at its top. Each of the lower and upper panels comprises a steel plate.

This substantially closed-loop structure has two opposed rectilinear sides 9, connected by respective front and rear end walls 10, 11.

The front end wall 10 is connected to the end of the opposed sides 9 to avoid any sharp edges.

In one embodiment, the front end wall 10 and the two sides 9 may be formed from a single profile by bending, although such walls may be also formed by joining several profile sections.

Preferably, the opposed rectilinear sides 9 and the front end wall 10 are oriented in such a manner that the respective open profile of the C faces towards the interior of the safety compartment V.

The rear portion Ib of the chassis has an end portion 12 at a higher level than said central portion Ic and two inclined sides 13 for connecting the end portion 12 to the central portion Ic. Preferably, these inclined sides 13 are connected to the substantially closed- loop structure at its rectilinear sides 9.

Essentially, the end portion 12 of the rear portion Ib of the chassis 1 is vertically offset upwards by a predetermined length L. This provides effective protection to the passenger P in case of collision. With reference to a side view of the chassis 1, a rectilinear side 9 of the portion Ic defines a substantially S-shaped profile with its respective inclined side 13 and the end portion.

Advantageously, the motor-generator unit comprising the current generator 16 and the internal combustion engine 18 may hang from the portion Ib of the chassis 1.

In case of collision, the driving unit and the rear generator that hang from the chassis are propelled to the ground. Particularly, in case of rear-end collision, this motor-generator unit may slip under the floor formed by the central portion Ic of the chassis 1, and is facilitated therefore in that the rear end wall 11 may be conveniently inclined to the vertical to converge downwards relative to the front end portion 10.

Advantageously, the front portion Ia of the chassis has two longitudinal members 23 projecting from said substantially closed-loop peripheral structure.

As shown in the figures, the two longitudinal members 23 extend parallel to the two opposed rectilinear sides 9 of the central portion Ic of the chassis 1, i.e. in said longitudinal direction. More particularly, the longitudinal members 23 overhang by a front portion 23a the front end wall 10 of the substantially closed- loop peripheral structure.

Advantageously, the two longitudinal members 23 extend into the substantially closed-loop peripheral structure by an intermediate portion 23b, so that said safety compartment V may be divided into multiple internal partitions.

Furthermore, the two longitudinal members 23 extend towards the back of the quadricycle 2 beyond the rear end wall 11 by a rear portion 23 c, where the distance between the two longitudinal members 23 increases, as shown in Figures 8 and 10. Essentially, the rear portions 23c of the longitudinal members 23 are more external to the quadricycle 2 than the front and central portions 23 a, 23 c, wherefore they can be conveniently used for supporting the rear wheels 3.

Preferably, each longitudinal member 23 has a transverse surface 24 whereby it abuts against the outer wall of the front end wall 10. As shown in the figures, the two longitudinal members 23 are at least partially higher than said substantially closed-loop sturdy structure.

Furthermore, the chassis 1 has a connecting cross member 25 which extends between the opposed rectilinear sides 9 to define a partition, within said safety compartment V, against the front end wall 10, in which the pressurized gas tank 20 may be received in a lying position. It shall be noted that the two longitudinal members extending above the tank 20 also have an effective downward retaining action on the tank 20.

Advantageously, the longitudinal guides of the front seat 7 are affixed to the floor formed by the central portion Ic of the chassis 1. Namely, the longitudinal guides of the front seat 7 are affixed to the longitudinal members 23. Preferably, the quadricycle 2 has at least one photovoltaic panel, for generating electric power and charging the accumulators. Advantageously, this photovoltaic panel is integrated in the roof of the quadricycle 2.

The front portion Ia of the chassis comprises support means 34 for supporting the front shock absorbers 31 and, similarly, the rear portion Ib comprises support means 35 for supporting the rear shock absorbers 32.

Advantageously, the upper load-bearing structure 30 (see Figure 12) associated with the chassis 1 extends from the rear portion Ib to the front portion Ia of the chassis 1, to be connected: - to the front portion Ia of the chassis 1 level with the support means 34 for the front shock absorbers 31 and

- to the rear portion Ib of the chassis 1 level with the support means 35 for the rear shock absorbers 32.

With reference to the illustrated embodiment, the upper load-bearing structure 30 comprises two opposed structural members 30a, each extending along its respective side of the quadricycle in the proximity of the roof 29.

In one embodiment, each of the two opposed structural members 30a comprises a sheet metal profile and localized reinforcement members, although tubular elements, profiles and the like may be also used. Advantageously, in the vicinity of the support means 34 for the front shock absorbers 31, the upper load-bearing structure 30 forms an extension of the front shock absorbers. In more detail, each of the two opposed structural members 30a forms an extension of its respective front shock absorber 34.

Each of the two opposed structural members 30a abuts by one of its ends against a base plate of the support means 34 for the front shock absorbers 31, in end connection with such base plate. Advantageously, the base plate 36 is oriented perpendicular to its respective structural member 30a of the upper load-bearing structure 30.

As shown with the support means 34 for the front shock absorbers 35, in the vicinity of the support means 35 for the rear shock absorbers 32, the upper load- bearing structure 30 forms an extension of the rear shock absorbers 32.

Namely, the upper load-bearing structure 30 extends from the support means 35 for the rear shock absorbers by respective pillars 30b connected to the opposed structural members 30a, such pillars 30b extending in a substantially vertical direction to form an extension of the rear shock absorbers 32.

Advantageously, a safety belt is associated with the front seat and a safety belt is also associated to the rear seat 8.

Both safety belts have multiple restraint points, typically two lower restraint points and one upper restraint point. While the lower restraint points are anchored to the chassis 1, the upper restraint point is advantageously secured to the upper load-bearing structure 30.

The quadricycle 2 further has two doors, connected by hinge connection means to the upper load-bearing structure 30. The two doors open independently of each other, and provide two exits in case of collision, for increased safety. Advantageously, the doors open in a fan-fold fashion, with a vertical rotation component, for optimized utilization of parking areas. For this purpose, each door is connected to the upper load-bearing structure 30 by hinge connection means 27, comprising:

- a stationary hinge part, comprising a stationary plate 40, fixed to the upper load-bearing structure 30, which has a stationary sleeve 41 projecting therefrom and extending along a hinge axis T-T substantially perpendicular to said longitudinal direction X-X and

- a movable hinge part comprising a movable plate 42, fixed to a door, which has a movable sleeve 43 projecting therefrom and extending along the hinge axis T- T.

Advantageously, the movable sleeve 43 is coaxially inserted by a predetermined length into the stationary sleeve 41, with antifriction means interposed therebetween, so that it can be operably coupled to said stationary sleeve 41 to be supported and rotatably guided relative to it about the hinge axis T-T. Engagement means are operable on said stationary hinge part and said movable hinge part to hold them in mutual engagement. In the example of Figures 16 and 17, these engagement means are embodied by a riveted pin 44 which engages the stationary plate 40 and the end of the movable sleeve 43.

These antifriction means are embodied by an annular layer of antifriction material interposed between the outer wall of the movable sleeve 43 and the inner wall of the stationary sleeve 41.

Furthermore, the end of said predetermined axial length of the movable sleeve 43 is spaced from the stationary plate 40 by an antifriction washer 45.

It shall be noted that, by suitably adjusting the position of the stationary plate 40 relative to the upper load-bearing structure 30 and of the movable plate 42 relative to the door, the door may be properly positioned and centered relative to the quadricycle structure.

The upper load-bearing structure 30 also support the roof 29 and a windshield. Advantageously, the quadricycle structure 2 comprises an AIR-BAG device which is located at a front portion of the quadricycle and is designed to deploy at the outer front portion of the safety cell of the quadricycle in case of collision. Essentially, such AIR-BAG is an AIR-BAG that operates outside the front portion of the quadricycle in case of front-end accident or collision. Furthermore, the quadricycle structure 2 comprises an AIR-BAG device which is located at a rear portion of the quadricycle and is designed to deploy at the outer rear portion of the safety cell of the quadricycle in case of collision. Essentially, such AIR-BAG is an AIR-BAG that operates outside the rear portion of the quadricycle in case of front-end accident or collision. As clearly shown in the above description, the quadricycle structure of the present invention fulfils the above mentioned needs and also obviates prior art drawbacks as set out in the introduction of this disclosure. Thus, as illustrated above, in case of front-end collision, the vertical stresses caused by the mass of the higher part of the quadricycle, as well as to the stresses transmitted by the safety belts that mostly act upon the upper load-bearing structure, may be easily discharged to the ground through the shock absorber supports, the shock absorbers and finally the wheels, by having the upper load-bearing structure form a closed loop on the shock- absorbers.

As a result, in spite of its very compact size, the quadricycle structure of the invention can provide a very efficient sturdy structure which exhibits a good behaviour to crash tests.

It shall be understood that the arrangement and conformation of the upper load-bearing structure relative to the shock-absorber supports and the shock- absorbers allows stresses to freely flow to the ground, with no undesired stress deviation. It shall be noted that the suspension arms can only transfer transverse and longitudinal loads and not vertical loads.

Furthermore, the possibility of optimized discharge of vertical loads through the shock absorbers and wheels allows improved braking behaviour of the quadricycle, particularly in terms of road grip of the front wheels.

An additional advantage of the quadricycle structure of the invention is the possibility of accommodating heavy components of the quadricycle, such as accumulators and the pressurized gas container in a low, protected position within the substantially closed-loop sturdy resistance of the chassis, so that they can be safely retained even in case of collision and that a low centre of mass of the vehicle can be maintained.

Furthermore, in case of front-end collision, the presence of the two longitudinal members overhanging the front of said substantially closed-loop sturdy structure can dissipate kinetic energy to the central part of the chassis. Indeed, the chassis of the invention has such a structure that, in case of front-end collision, the important masses of the quadricycle are discharged in the longitudinal direction of extension of the two longitudinal members subjected to deformation, while the driving unit and the rear generator hanging from the chassis are propelled to the ground. Another advantage of the quadricycle structure of the present invention is the ability of achieving the required rigidity and strength with a low- weight structure.

Those skilled in the art will obviously appreciate that a number of changes and variants may be made to the quadricycle structure as described hereinbefore, in response to specific requirements, without departure from the scope of the invention, as defined in the following claims.

Claims

1. A motor quadricycle structure comprising:

- a chassis (1); - a body that defines an interior compartment;

- a plurality of wheels (3) for ensuring stable support of the quadricycle on the ground;

- front shock absorbers (31) and rear shock absorbers (32) associated with said wheels (3); - motor means (14) for allowing said quadricycle to move; and

- a front seat (7) for a driver, characterized in that it has an upper load-bearing structure (30) supported by said chassis (1), for defining with said chassis (1) a safety cell in which a driver (D) of the quadricycle can be received in a protected position.

2. A quadricycle structure as claimed in claim 1, wherein said chassis comprises a front portion (Ia) having support means (34) for supporting the front shock absorbers (31) and a rear portion (Ib) having support means (35) for supporting the rear shock absorbers (32), said upper load-bearing structure (30) extending from said rear portion (Ib) to said front portion (Ia) of said chassis (1), characterized in that said upper load-bearing structure (30) is connected to the front portion (Ia) of said chassis level with said support means (34) for the front shock absorbers (31).

3. A quadricycle structure as claimed in claim 2, wherein said upper load- bearing structure (30) is connected to the rear portion (Ib) of said chassis (1) level with the support means (35) for the rear shock absorbers (32).

4. A quadricycle structure as claimed in claim 2 or 3, wherein said upper load- bearing structure (30) comprises two opposed structural members (30a), each extending along its respective side of the quadricycle (2).

5. A quadricycle structure as claimed in claim 4, wherein said opposed structural members (30a), extend in the proximity of the roof (29) of the quadricycle

(2).

6. A quadricycle structure as claimed in claim 4 or 5, wherein each of said opposed structural members (30a) comprises a metal sheet profile and localized reinforcement elements.

7. A quadricycle structure as claimed in claim 4 or 5, wherein each of said opposed structural members (30a) is a tubular element.

8. A quadricycle structure as claimed in any one of claims 2 to 7, wherein in the vicinity of said support means (34) for the front shock absorbers (31), said upper load-bearing structure (30) forms an extension of said front shock absorbers (31).

9. A quadricycle structure as claimed in any one of claims 4 to 7, wherein in the vicinity of said support means (34) for the front shock absorbers (31), each of said opposed structural members (30a) forms an extension of said front shock absorbers (31).

10. A quadricycle structure as claimed in claim 9, wherein each of said opposed structural members (30a) abuts by one of its ends against a base plate (36) of said support means (34) for the front shock absorbers (31).

11. A quadricycle structure as claimed in claim 10, wherein said base plate (36) is oriented perpendicular to its respective structural member (30a) of the upper load- bearing structure (30).

12. A quadricycle structure as claimed in any one of claims 2 to 11, wherein said upper load-bearing structure (30) is connected to said support means (34, 35) for the shock absorbers (31, 32) by removable connection means.

13 A quadricycle structure as claimed in claim 3, wherein in the vicinity of said support means (35) for the rear shock absorbers (32), said upper load-bearing structure (30) forms an extension of said rear shock absorbers (32).

14. A quadricycle structure as claimed in claims 4 and 13, wherein said upper load-bearing structure (30) extends from said support means (35) for the rear shock absorbers (32) by respective pillars (30b) connected to said opposed structural members (30a), said pillars (30b) forming an extension of said rear shock absorbers (32).

15. A quadricycle structure as claimed in any one of claims 2 to 14, comprising a safety belt associated with said front seat (7), wherein at least one restraint point of said safety belt is secured to said upper load-bearing structure (30).

16. A quadricycle structure as claimed in any one of claims 2 to 15, comprising a back seat (8) with a safety belt associated therewith, and having at least one restraint point secured to said upper load-bearing structure (30).

17. A quadricycle structure as claimed in any one of claims 2 to 16, comprising two doors, connected by hinge connection means to said upper load-bearing structure (30).

18. A quadricycle structure as claimed in any one of claims 2 to 17, comprising a roof (29) and a windshield supported by said upper load-bearing structure (30).

19. A quadricycle structure as claimed in any one of claims 2 to 18, wherein said front seat (7) is supported relative to said chassis for rotation about an axis substantially perpendicular to a seat surface, to orient said front seat to one said of said quadricycle.

20. A quadricycle structure as claimed in claim 19, comprising removable engagement means for engaging said front seat (7), to hold said front seat (7) in a first angular position in which said front seat (7) is oriented in the direction of travel to receive a driver during driving, said engagement means being releasable by the driver to allow said front seat to rotate to one side of said quadricycle.

21. A quadricycle structure as claimed in any one of claims 1 to 20, comprising:

- at least one electric motor (14) kinematically connected to the wheels (3) for driving them into rotation or acting as an electrodynamic brake on them.

22. A quadricycle structure as claimed in claim 21, wherein: - a differential unit (19) is located between two opposed driving wheels (3) and connected to said wheels via respective axle shafts;

- the drive shaft (21) of said electric motor (14) extends in a longitudinal direction substantially perpendicular to the transverse direction of extension of said axle shafts and has an end located substantially below said differential unit - a gear train (22) kinematically connects the drive shaft (21) of said electric motor (14) with said differential unit (19);

- said gear train (22) comprises a crown wheel and pinion, with a bevel pinion (26) integrally rotatably connected to said free end of said drive shaft (21).

23. A quadricycle structure as claimed in claim 21 or 22, comprising: - a motor generator which is designed to act as a power source for supplying power to said electric motor (14) and/or charging accumulators (15),

- a photovoltaic panel for generating electric power for charging said accumulators (15), said photovoltaic panel being integrated in the roof of the quadricycle (2), wherein said motor-generator comprises a current generator (16) rotatably connected to the drive shaft of an internal combustion engine (18), said internal combustion engine (18) being a four- stroke cycle engine with a contra-rotating balance shaft, which is selectively powered with gas or liquid fuel of fossil and/or vegetable origin.

24. A quadricycle structure as claimed in any one of claims 1 to 23, comprising an AIR-BAG device which is located at a front portion of said quadricycle and is designed to deploy at the outer front portion of said safety cell of the quadricycle in case of collision.

25. A quadricycle structure as claimed in any one of claims 1 to 24, comprising an AIR-BAG device which is located at a rear portion of said quadricycle and is designed to deploy at the outer rear portion of said safety cell of the quadricycle in case of collision.

26. A quadricycle structure as claimed in claim 17, wherein said hinge connection means (27) comprise:

- a stationary hinge part, comprising a stationary plate (40), fixed to said upper load-bearing structure (30), which has a stationary sleeve projecting therefrom and extending along a hinge axis (T-T);

- a movable hinge part comprising a movable plate (42), fixed to a door, which has a movable sleeve (43) projecting therefrom and extending along said hinge axis (T-T); wherein:

- said movable sleeve (43) is operably coupled to said stationary sleeve (41), with antifriction means interposed therebetween, to be supported and rotatably guided relative to the stationary sleeve (41) about said hinge axis (T-T);

- engagement means (44) are operable on said stationary hinge part and said movable hinge part to hold said stationary hinge part and said movable hinge part in mutual engagement and

- said hinge axis (T-T) extends in a direction transverse to the longitudinal direction in which said quadricycle extends from a front portion (Ia) to a rear portion (Ib), to allow said doors to open in fan-fold fashion in a vertical plane relative to the ground.

27. A quadricycle structure as claimed in claim 26, wherein:

- said movable sleeve (43) is coaxially inserted by a predetermined axial length into said stationary sleeve (41) and

- the end of said predetermined axial length of said movable sleeve (43) is spaced from said stationary plate (40) by an antifriction washer (45).

28. A quadricycle structure as claimed in any one of claims 1 to 27, having a longitudinal size (A) of 2,0÷2,4 m and a transverse size (B) of 0,9÷l,2 m.

29. A quadricycle structure as claimed in any one of claims 1 to 28, having an overall dry weight of less than 500 kg.